Process for producing lenses and the product



Nov. 3,1925. 1,560,168

M. A. LAABS PROCESS FOR PRODUCING LENSES AND THE PRODUCT Filed April 27, 1925 fi I v max abaabs.

Patented Nov. 3, 1925.

UNITED STATES PATENT OFFICEL MAX A. LAAIBS, OF SOUTHBRIDGE, MASSACHUSETTS, ASSIGNOR TO AMERICAN OPTICAL COMPANY, OF SOUTHBRIDGE, MASSACHUSETTS.

MASSACHUSETTS, A VOLUNTARY ASSOCIATION OI PROCESS FOR'PRODUCING LENSES AND THE IPBODUCT.

Application filed April 27, 1925. Serial No. 28,159.

To all whom it may concern:

Be it known that I, MAX zen of the United States, residing at Southbridge, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Processesfor Producing Lenses and the Products, of which the following is a specification.

This invention relates to improvements in the manufacture of lens blanks and finished lenses, and has particular reference to the provision of an improved rocess for the production of multifocal op thalmic lenses. An important object of this invention is to provide an improved process for the production of mult'ifocal lenses, and more particularly those composed of two different kinds of glass known in the art as Kryptoks. Another object is to provide such a process whereby standard rough nultifocal blanks may be changed to provide any desired optical addition through the reading portion. Another object is to provide such a process whereby special additions in the reading portion may be readily ob'tained.

Another object is to provide such a process which will be simple, economical and reliable in application to lens manufacture.

Other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings, wherein is shown by way of illustration certain preferred steps in the process.

In the drawings, wherein similar reference characters designate corresponding parts:

Figure '1 is a transverse sectional view through the major portion of the lens blank;

Figure 2 is a similar view' through'the minor portion of the blank;

Figure3 is a sectional view showing the major and minor'portions in their assembled relationship Figure 4 is a similar view illustrating the preparation o'f'a standard blank for a variation of its reading addition;

Figure 5 is a similar view of a. lens blank on its supporting block after the addition has been, changed; a j

Figure 6 is a sectional view through a finished lens made from the blank;

Figure '7 is a front elevation thereof;

Figure 8 is a view similar to Figure'5, showing a modified form of the invention.

A. LAABS, a citih on the outer In the production of multifocal lenses it as been necessary in order to supply the various demands of the trade, to produce a great many different blanks each having a different optical addition through its readng port1on. The production and carryin in stock of so many different styles of blanks has naturally been expensive and has re gulred a great many extra tools tovbe used 1n the factory. This is particularly true in the case of lenses and blanks formed from two p eces of different kinds of glass, one of wh1ch being set into a recess in the other, since the addition' of such cases is dependent upon the curve of the recess and that of. the member secured in the recess.

It is an object of the present invention to overcome the necessity for carrying so many and tools in stock, and to thereby simplify the manufacture and 1 reduce the cost ef the same.

I-n carrying out the invention a lens blank 7 10, preferably formed of crown glass, is provided on one of its surfaces with a ound and polished recess or countersink 11, which may preferably be either spherical or toric 1n form. A minor lens member 12 having a different refractive index from that of the major portion 10 and referably formed from flint glass is provided with a convex curved surface 13 ground and polished and substantially contrageneric to the recess 11. These two lens memberslO and 12 are then placed in proper relationship to each other so that the flint button 12 may be secured within the recess 11 such as by fusing. The particular steps of the fusing operation are well known to those skilled in the artand, therefore, it is not thought necessary to go into the details thereof in this case. In this manner a standard Kryptok blank is produced which will have a certain optical addition through the reading portion or button 12, and by combining difi'erent curves surfacesof'the blank any one of a number of different finished lenses may be produced.

However, it is necessary to have lefiEs with different additions throughthe reading portion, and to accomplish this I provide the blank with a second recess 14 shown in Figure 4. I then place the blank upon a block 15 of refractory material, such as carborundum, graphite, etc., and soften the blank by the action of heat, whereupon the material above the recess 14 will sag down, as shown in Figure 5. As the material ofthe blank sags down into the recess 14 the curve 11 which is the surface of joinder between the flint and glass members, will be displaced to a stronger curve than what it was originally. The amount of such displacement can be readily controlled by the radius of curvature of the recess 14 and by its depth.

As one specific example I have taken a standard blank having a minus 6 diopter base curve on the inner side of the blank, and a plus 4.50 diopter curve in the recess 11. By providing such a blank with a recess 14.- having a minus 6.87 diopter curve and then allowing it to sag down, as ex planed, the optical addition 'throu h the reading portion will be equal to 8 hundredths of a diopter. In other words, the final optical addition through the reading portion will be plus 5.37 instead of plus 4.50.

The advantages of this will be readily seen from the fact that all of the flint buttons 12 may be produced with the same radius of curvature 13, and any of the standard blanks may be finally rendered to the desired optical addition by the improved process. After the blank has been thus formed, proper optical surfaces 16 and 17 may be formed upon the opposite sides of the blank to produce a finished lens, as shown in Figures 6 and 7, wherein the crown glass 10 provides a distance vision portion and the flint button 12 provides the reading portion of a bifocal lens.

In Figure 8, I have illustrated a modification of the invention, whereby the surface of joinder of thetwo glass members maybe displaced by dropping a portion of the lens into a recess. For example, the lens blank 10', similar to that shown in Figure 3, may be supported upon a refractory block 18 which is provided in its upper surface with a countersink or recess 19 of the desired curvature. Upon heating the blank 10 while resting on the block 18, a portion of the material will sag into the recess 19 in the block and thus displace the line of joinder between the two glass members.

The process is. simple in its application to commercial use and has been proven to be entirely practical. By it the cost of manufacturing lenses of this type can be considerably reduced and the results obtained are equalin quality to those 'of the prior art processes.

' Obviously other modifications may be made in the various details and in the steps of the process, and the right is herein reserved to make such changes'as fall within the scope of the appended claims without departing from the spirit of the invention.

Having thus described my invention, 1 claim:

1. A process for producing multifocal lens blanks consisting in forming a major portion with a recess in one of its surfaces, securing a button of a different refractive index in the recess, countersinking the opposite surface of the major portion behind the button, and bending the major portion and button to change the surfacesof the recess and button.

2. A process for producing multifocal lens blanks consisting in forming a major portion with a recess in one of its surfaces, fusing a button of a different refractive index in the recess, forming a depression in the opposite side of the major portion and behind the button, heating the blank and causing part of the major portion and the button to be bent toward the depression on the opposite side. 3. A process for producing multifocal lens blanks consisting in forming a major portion with a recess in one of its surfaces, securing a button of a different refractive index in the recess, softening the two members, by heating, and displacing part of the major portion and button to change the optical addition through that portion of the blank.

4. A process for producing multifocal lens blanks consisting in forming a major portion with a recess in one of its surfaces, securing a button of a difierent refractive index in the recess, softenin the two members by heating, and increasing the amount of optical addition through the button by bending while in softened condition.

5. A- process for producing multifocal lens blanks consisting in providing a two part fused bifocal blank with a depression opposed to the optical addition, and bending a portion of the blank into said depression to increase the amount of the optical addition.

6. A process for producing multifocal lens blanks consisting in providing a two part fused bifocal blank with a depression opposed to the .optical addition, supporting said blank on a refractory block, heating the blank to 'soften it, and allowing a portion of the material to sag into the recess to deform the surface of joinder of the two pieces of-glass constituting the blank.

71A process for producing multifocal lens blanks consisting in forming a crown glass major portion with opposed recesses in its surfaces,forming a flint glass button with a curve contrageneric to that of one of the recesses, securing the button in its recess in the major portion, heating the crown and flint members to soften them, and displacing a portion of the crown glass into the second recess to change the curve of the first recess and button, substantially as set forth.

8. A process for producing bifocal lenses consisting in forming a two part fused bifocal blank with a, depression opposed to the optical addition, bending a portion of the blank into said depression to increase the amount of the optical addition, and subsequently finishing the surfaces of the blank to continuous curves.

9. A process for producing multifocal lenses consisting in forming a major portion with a recess in one of its surfaces, securing a button of a different refractive index in the recess, softening the two members by heating, displacing part of the major portion and button to produce the desired 0 tical addition through that portion of ti ie lens, and subsequently finishing the surfaces of the blank to continuous optical curves.

10. A blank for a multifocal lens comprisin? a major portion having a recess on one si e finished to an optical surface, and a recess on the opposite side in alignment with the first recess.

11. A blank for a multifocal lens comprising a major portion having a recess finished to an optical surface, a minor portion of different index of refraction secured in the recess, and a recess on the other side of the major blank in alignment with the first re cess. v

MAX A. LAABS. 

